The present invention relates to a tranexamic acid-peptide having skin whitening activity and a use thereof, and more specifically, to a tranexamic acid-peptide of a particular sequence with an excellent skin whitening effect, thermal stability, and storage stability, and a use thereof.
Skin is the largest tissue in the body and functions to protect the body from sunlight, physical and chemical stimuli, and it is absolutely necessary for the maintenance of human life and is constantly regenerated to maintain homeostasis. The skin is composed of the epidermis, the dermis, and the subcutaneous fat in order from the outer side. The epidermis, which is the thinnest tissue of the skin, plays an important role of moisturizing and protecting the skin, and is responsible for preventing water loss, damage, bacterial invasion, etc. Skin is a tissue that surrounds the entire body and has various functions. Because it has a barrier function between the inside and the outside of the body, it has an immune system by the islets of Langerhans and a moisture control function by the epidermis. Additionally, it performs the synthesis of vitamin D under a proper sunlight and also the excretion into the lipid reservoir and sweat glands. The stratum corneum produced by the normal differentiation process in healthy skin has the function of maintaining the moisturization of the skin and protecting it from the stimulation of the external environment. This function is called the skin barrier function and it may be the most important role of the epidermis.
Activity of many enzymes involved in melanin synthesis and skin tone with regard to skin whitening, one of the major effects of cosmetics, have been elucidated. However, the reasons why the skin color of Asian people is particularly susceptible to deposits and aging have not yet been identified. Materials that are believed to reveal skin tone are typically known to inhibit melanin synthesis and each of the enzymes involved therein.
A person's skin color varies depending on various factors, in particular season, race, and sex, and it is mainly determined by the amount of melanin, carotene, and hemoglobin, and among these, melanin is the most crucial factor. Melanin is synthesized in melanocytes present in the basal layer of the skin and transferred into adjacent keratinocytes thereby exhibiting the human skin colors. It is known that when the melanin level is abnormally low, skin lesions such as vitiligo are induced, whereas when melanin is produced excessively, spots and blemishes are formed. Melanin is produced by the action of tyrosinase on tyrosine (i.e., a kind of amino acid), tyrosinase is more activated by ultraviolet rays. Therefore, when the skin is exposed excessively to sunlight, it turns black. Cosmetics in the concept of the skin whitening effect are establishing a big market in Korea, Japan, etc. and these products are prepared by combining materials that usually have the inhibitory effect against tyrosinase.
Recently, the activity of many enzymes related to melanin synthesis and skin tone has been elucidated, however, the reasons why the skin color of Asian people is particularly susceptible to deposits and aging have not yet been identified. Materials that are believed to reveal skin tone are typically known to inhibit melanin synthesis and each of the enzymes involved therein.
Conventionally, examples of the raw materials that can be incorporated into skin whitening cosmetics as an inhibitor of tyrosinase activity not only include plant extracts (e.g., ascorbic acid (vitamin C) and derivatives thereof, a Morus alba L. extract, a green tea extract, an aloe extract, a Scutellaria radix extract, etc.), but also include kojic acid, Arbutin, an oil-soluble licorice extract, tranexamic acid, amide, etc. However, various plant extracts have a problem in that they are unstable, and the effects cannot be sustained when mixed into a product and that their effects of inhibiting tyrosinase activity are not significant. Additionally, kojic acid is commonly used as a tyrosinase inhibitor but it has problems in that it is difficult to prepare it as a composition because it may cause allergic reactions (Nakagawa M. et. al., Contact Dermatitis, 43: PP9-3(1995)), and that it should be used in an excessive amount close to 2% because it is unstable in products.
Tranexamic acid is an analog of lysine, which is a kind of amino acid. It has been widely used as a hemostatic agent in pharmaceutical field and it is a material which has been proved with regard to its administration frequency and safety so as to be one of the essential drugs prescribed by the World Health Organization. Tranexamic acid has the role of aiding the hemostatic activity by inhibiting the activation of the active site of plasmin, an anticoagulant in the blood. However, plasmin not only promotes blood clotting but also promotes the growth of melanocytes, which are the cells that produce melanin, and simultaneously, activates the production of arachidonic acid, which is the precursor of prostaglandins and leucotrienes that promote the production of melanin. Therefore, plasmin has a significant effect on the intracellular melanin production and helps skin whitening by inhibiting the activity of plasmin.
Meanwhile, various attempts have been made to develop various whitening agents using peptides, but their effects were not significant. Additionally, there was a difficulty in the manufacture of vitamin C-peptide complexes and hydroquinone peptide complexes for the purpose of maximizing the whitening effects, and its use was limited due to the high cost, and thus its application in the market was not remarkable.
The majority of whitening functional materials currently on the market are focused on alleviating the symptomatic parts by eliminating the sites for melanin pigment accumulation, and conventional dermatologic procedures also aim at artificially removing these accumulation sites through a laser.
Removing only these symptomatic parts may have a short-term effect, however, it does not accompany an improvement in the turnover, which is the principal cause, and thus a side effect occurs that melanin accumulates again in a short period of time. Accordingly, if it is possible to restore the skin's normal turnover cycle, and prevent and eliminate hyperkeratosis of the skin through moisturizing action, it is expected that the principal cause of the pigment accumulation can be resolved instead of an attempt being focused on resolving symptomatic matters, and a change into a healthy skin may be achieved.